Working Group 2

Theory group led by Bojan Vrsnak (Croatia) and Yuming Wang (China)

Objectives

• Initiation of CMEs and their take-off dynamics ("acceleration stage")
• Heliospheric dynamics of ICMEs and evolution of their structure
• Relationship between empirical, analytical, and numerical propagation models and comparison with observations; forecasting aspects
• CME/ICME-associated phenomena (flares, shocks, etc.)

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Scientific Questions

Which mechanisms, processes, forces are governing the CME take-off and ICME propagation?

2.1.1 What is the role of the flare-associated reconnection?

2.1.2 What is the role of emerging flux and poloidal-flux injection? 2.1.3 How long the Lorentz force dominates over the aerodynamic drag 2.1.4 How the inductive effects affect the CME eruption and ICME propagation? 2.1.5 What is the role of the ICME/ambient-field reconnection?

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How much variable ambient conditions affect ICMEs?

2.2.1 Which processes are involved in ICME-ICME interactions? 2.2.2 How ICME-ICME interactions affect the dynamics and structure of ICMEs? 2.2.3 How high-speed solar wind streams (corotating interacting regions) affect ICMEs? 2.2.4 How the ICME-driven shock evolves in the decreasing Alfven-velocity environment?

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What is the state of the art in the ICME-arrival and ICME-geoeffectiveness forecasting?

2.3.1 What are forecasting-performances of various empirical, analytical, and numerical models? 2.3.2

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